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Abstract:

In one embodiment, a nuclear magnetic resonance (NMR) apparatus is
described. The example NMR apparatus includes a first field generator
configured to apply a first magnetic field to a sample (e.g., blood,
interstitial fluid). A pulse generator is configured to provide a radio
frequency (RF) pulse sequence. The pulse sequence may include a first RF
pulse and a second RF pulse. The frequency of the RF pulses is chosen to
produce an NMR signal associated with a specific chemical species (e.g.,
glucose) in the sample. A phase logic is configured to measure the decay
of the NMR signal by measuring the phase differences that have
accumulated between the spins of the nuclei of the chemical species in
the sample. A calculation logic is configured to measure the amount of
the chemical species in the sample.

Claims:

1. A nuclear magnetic resonance (NMR) apparatus, comprising: a first
field generator configured to provide a first magnetic field suitable for
NMR; a pulse generator configured to provide a radio frequency (RF)
sequence at a frequency configured to produce an NMR signal in nuclei
associated with a chemical species in a sample located in the first
magnetic field; a phase logic configured to measure NMR signal decay; and
a calculation logic configured to measure an amount of the chemical
species in the sample as a function of the NMR signal decay.

2. The NMR apparatus of claim 1, where the chemical species is glucose,
and where the sample is a sample of interstitial fluid.

3. The NMR apparatus of claim 1, where the NMR apparatus is one of,
mobile, wearable, and implantable.

4. The NMR apparatus of claim 1, comprising a therapeutic logic
configured to determine an amount of insulin to be administered to a
patient as a function of the measure of the amount of the chemical
species in the sample.

5. The NMR apparatus of claim 4, comprising an insulin pump configured to
administer the amount of insulin to the patient.

6. The NMR apparatus of claim 5, where the insulin pump comprises a
feedback logic configured to adjust the amount of insulin administered to
the patient as a function of a change in the measure of the amount of the
chemical species in the sample.

7. The NMR apparatus of claim 1, where the first magnetic field is a
static inhomogeneous applied magnetic field configured not to change in
time.

8. The NMR apparatus of claim 1, where the pulse sequence comprises a
first RF pulse to excite nuclei associated with a chemical species in a
sample and a second RF pulse to cause the nuclei of the chemical species
to rephase according to their spatial position in the first magnetic
field.

9. The NMR apparatus of claim 1, comprising a second field generating
apparatus configured to provide a second magnetic field, where the
superposition of the first magnetic field and the second magnetic field
is spatially inhomogeneous.

10. The NMR apparatus of claim 9, where the second magnetic field is one
of, a pulsed field gradient, and a constant field gradient.

11. The NMR apparatus of claim 1, where the NMR signal decay represents
decay due to diffusion.

12. The NMR apparatus of claim 1, where the NMR signal decay represents
the intrinsic relaxation of the chemical species.

13. The NMR apparatus of claim 1, where the NMR signal decay is measured
by comparing a plurality of NMR signals acquired after the pulse
generator has provided the RF sequence a plurality of times.

14. A method, comprising: controlling a NMR apparatus to apply a first
magnetic field to a sample in a patient and to apply a RF signal to
produce an NMR signal in nuclei associated with a chemical species in the
sample; acquiring NMR signal decay data associated with a decay of the
NMR signal produced in response to applying the first magnetic field and
the RF signal; and producing a characterization of a chemical species in
the sample as a function of the NMR signal decay data.

15. The method of claim 14, where producing the characterization
comprises identifying an amount of the chemical species in the sample.

16. The method of claim 14, comprising: controlling an insulin providing
apparatus to provide a first dosage of insulin to the patient based, at
least in part, on the amount of the chemical species in the sample.

17. The method of claim 16, comprising: controlling the insulin providing
apparatus to provide a second, different dosage of insulin to the patient
based at least in part, on a change in the characterization of the
chemical species in the sample.

18. The method of claim 14, comprising: controlling the NMR apparatus to
apply a second magnetic field to the sample.

19. The method of claim 18, where the NMR apparatus is controlled to
apply the first magnetic field and the second magnetic field in a manner
that produces a spatially inhomogeneous field.

20. The method of claim 19, where the NMR apparatus is controlled to
apply the second magnetic field as one of a pulsed field gradient and a
constant field gradient.

21. The method of claim 14, where the NMR apparatus is at least one of
mobile, and wearable.

22. A system for determining an amount of a chemical species in a solvent
in a patient, comprising: means for applying a static inhomogeneous
magnetic field to the solvent; means for applying a spatially
inhomogeneous magnetic field to the solvent; means for applying a RF
signal to produce a NMR signal in nuclei associated with the chemical
species in the solvent, where the solvent is in the static inhomogeneous
magnetic field and the spatially inhomogeneous magnetic field; means for
characterizing a decay of the NMR signal; means for characterizing the
amount of the chemical species in the solvent based, at least in part, on
the decay; means for administering a dosage of insulin to a patient,
where the dosage amount is a function of the characterization of the
chemical species in the solvent; and means for adjusting the dosage of
inulin to the patient based, at least in part, on a change in the
characterization of the chemical species in the solvent.

Description:

BACKGROUND

[0001] According to NIH Publication No. 99-4398, in 1999, diabetes
affected an estimated 16 million Americans. As of 1999, about 800,000 new
cases were diagnosed annually. In 1999, diabetes was the sixth leading
cause of death due to disease in the United States. Since 1980, the
age-adjusted death rate due to diabetes has increased by 30 percent. Over
the same time period the death rate has decreased for other common
multifactorial diseases (e.g., cardiovascular disease, stroke). In 1999,
the cost of diabetes to the United States was over $105 billion. More
than one out of every ten U.S. health care dollars was spent for
diabetes. About one out of every four Medicare dollars was spent on
health care for people with diabetes.

[0002] Diabetes Mellitus, which is commonly referred to more concisely as
diabetes, is a chronic disease that affects the ability of the body to
maintain desired blood sugar levels. Type 1 diabetes occurs when the
pancreas is unable to produce insulin in amounts sufficient to properly
control blood sugar levels. Type 1 diabetes may occur when the body
actually attacks and destroys cells that are supposed to produce insulin.
Thus, type 1 diabetes is considered to be an autoimmune disease in which
unknown environmental factors combine with genetic susceptibility to
destroy pancreatic beta cells that produce insulin in healthy humans.

[0003] The pancreas is supposed to produce two hormones that together act
to maintain desired blood sugar levels. Insulin is supposed to be
produced when blood glucose levels get too high. Insulin instructs the
body's cells to take in glucose from the blood. Glucagon is supposed to
be released when blood glucose levels start to fall too low. Glucagon
instructs the liver to convert stored glycogen into glucose and release
it into the bloodstream. The action of glucagon is thus opposite to that
of insulin. Glucagon also stimulates the release of insulin, so that
newly-available glucose in the bloodstream can be taken up and used by
insulin-dependent tissues. A diabetic pancreas does not produce
appropriate hormones in appropriate amounts at appropriate times, and
thus, blood glucose levels can reach undesired levels. Thus, the key
characteristic of type 1 diabetes is the inability to manufacture desired
amounts of insulin.

[0004] Even though the causes are different, a similar set of dysfunctions
occur with Type II diabetes. In Type II diabetes, the cells of the body
are unable to receive or transport the sugars from the blood stream into
the cells, again leading to a lack of control of blood glucose
concentration.

[0005] Undesired blood glucose levels can include too much sugar in the
blood (hyperglycemia) and too little sugar in the blood (hypoglycemia).
Eating can increase blood sugar levels. Insulin can lower blood sugar
levels. Therefore, all people with type 1 diabetes and some with type II
take insulin.

[0006] Historically, insulin has been injected under the skin. To achieve
the goal of maintaining blood sugar levels in a desired range, diabetics
will frequently test their blood sugar levels. Based on the measured
blood sugar level, diabetics will ideally inject an appropriate amount
and type of insulin at an appropriate time.

[0007] Recently, insulin pumps have been used to deliver insulin
continuously and/or periodically. Insulin pumps may be programmed to
deliver insulin in set amounts at set times. Some insulin pumps may even
be programmed to deliver different amounts on demand based on blood sugar
level measurements.

[0008] Determining insulin dosage and delivery time depends on accurately
measuring blood sugar levels. Conventionally, measuring blood sugar
levels has been performed by chemically analyzing blood or interstitial
fluids. Chemically analyzing blood has conventionally required access to
blood and then sacrificing the accessed blood during the chemical test.
To acquire the blood a diabetic may prick their finger to get a blood
drop. The diabetic will then put the drop of blood in a glucose meter and
read the measurement. Alternatively, a probe (e.g., catheter) may be
inserted into the body to maintain substantially constant access to a
blood or interstitial fluid source.

[0009] Both the finger prick technique and the inserted probe technique
are invasive, can be painful, and can provide entry points for bacteria,
virus, and infection. Furthermore, since both techniques involve a
chemical reaction, the measurements may not always be as accurate as
desired. Also, when the diabetic has to read the measurement from the
device, there is an opportunity for the measurement to be misread. These
inaccuracies can lead to inappropriate amounts of insulin being delivered
at inappropriate times.

[0010] Issues associated with inaccurate blood sugar level measurements
are exacerbated by the fact that different insulin preparations have
different characteristics. For example, different insulin preparations
may begin working at different times, may work at different rates, and
may work for different periods of time. Making things even worse,
different insulin preparations may act differently under different
conditions (e.g., age of preparation, exposure to heat, exposure to other
chemicals). Conventionally it may have been difficult for the diabetic,
especially under certain conditions (e.g., stress, shock) to compute
proper dosages and/or mixtures. Thus, it becomes even more likely that
inappropriate amounts of insulin can be delivered at inappropriate times.
Even if accurate measurements were taken and accurate dosages computed,
the actual effect of the injected insulin can only be analyzed by a
subsequent measurement.

[0011] A diabetic may experience different insulin demands from day to
day, and even from moment to moment as a function of activity, stress,
environmental factors, and so on. Therefore, the diabetic may need to be
provided with different amounts of insulin when exercising, when sick,
when eating more or less than normal, when travelling, when under stress,
and under other conditions. However, the conditions that produce the
varying needs may also make it difficult, if even possible at all, to
make an accurate blood sugar level measurement. Particularly difficult
conditions for monitoring blood sugar levels and delivering appropriate
amounts of insulin include during surgery, during high intensity
exercise, while asleep, while in a coma, during childbirth, while
suffering from dementia, while suffering from Alzheimer's, and so on.

[0012] Therefore, attempts are constantly being made to improve blood
sugar level measurement techniques and accuracy and to identify feedback
mechanisms to facilitate delivering appropriate amounts of insulin at
appropriate times.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The accompanying drawings, which are incorporated in and constitute
a part of the specification, illustrate various example systems, methods,
and other example embodiments of various aspects of the invention. It
will be appreciated that the illustrated element boundaries (e.g., boxes,
groups of boxes, or other shapes) in the figures represent one example of
the boundaries. One of ordinary skill in the art will appreciate that in
some examples one element may be designed as multiple elements or that
multiple elements may be designed as one element. In some examples, an
element shown as an internal component of another element may be
implemented as an external component and vice versa. Furthermore,
elements may not be drawn to scale.

[0014] FIG. 1 illustrates an embodiment of an NMR apparatus to measure an
amount of the chemical species in a sample.

[0017] FIG. 4 illustrates an embodiment of an NMR apparatus configured
with a second field generating apparatus.

[0018] FIG. 5 illustrates a method associated with measuring an amount of
chemical species in a sample associated with an NMR apparatus.

[0019] FIG. 6 illustrates a method associated with measuring an amount of
chemical species in a sample associated with an NMR apparatus.

DETAILED DESCRIPTION

[0020] Example systems and methods non-invasively and accurately measure
blood sugar glucose levels substantially constantly and substantially in
real-time. Example systems and methods employ diffusion nuclear magnetic
resonance (NMR) to non-invasively determine blood glucose levels. Blood
cells, other cells, and fluid in intercellular spaces will produce
different NMR signals as a function of different blood glucose levels.
Diffusion speed in the interstitial fluid is affect by the amount of
glucose in the fluid. Therefore, the described NMR methods can be used to
measure blood glucose levels.

[0021] Envision a twelve ounce glass filled with six ounces of pure water.
Now envision adding one tablespoon of sugar to the water. Adding the
tablespoon of sugar to the water changes the water. Now envision adding
ten or a hundred tablespoons of sugar to the water. Understandable
properties of the water will change as the amount of sugar in the water
changes. For example, the viscosity of the water will change. Similarly,
the transparency of the water may change. In particular, the amount of
glucose in a fluid affects diffusion. The higher the glucose level, the
lower the diffusion of the water through the solution. This effect is
observable using NMR techniques.

[0022] Example systems and methods facilitate acquiring NMR signals from
the water and monitoring their decay rates under defined situations. The
NMR signals accurately measure the amount of sugar in the water and/or
the change in the amount of sugar in the water. The NMR signals are
acquired without touching the water. Thus, example systems and methods do
not require a finger stick or an embedded sensor that is in contact with
blood to be able to measure blood sugar levels.

[0023] Example systems measure the decay of the NMR signal in the presence
of either a switched or constant inhomogeneous applied magnetic field.
Example systems may employ a constant inhomogeneous main magnetic field,
or a gradient field. One example system measures the apparent NMR signal
decay rate using an inhomogeneous permanent magnet as the polarizing
field for the NMR experiment. Another example system performs
conventional diffusion weighted NMR using pulsed or constant field
gradients.

[0024] Conventionally, NMR systems have been room-sized. Therefore,
conventionally it has been impractical to measure blood sugar levels for
diabetics using an NMR system. It is impractical to live inside an MRI
apparatus. Therefore, example systems provide miniaturized apparatus that
produce very local conditions sufficient to perform very local NMR.
Example methods employ the miniaturized apparatus to acquire NMR signals.
The NMR signals are then analyzed to determine blood sugar levels. In one
embodiment, the blood sugar levels determined from the NMR signals are
then used to control an insulin pump.

[0025] NMR spectroscopy provides a non-destructive, quantitative
analytical method. Many organic molecules have NMR-active nuclei.
Diffusion constants for molecular sized objects in solution can be
measured using NMR. The diffusion constants can be measured with an
accuracy approaching 1%. Example systems and methods employ diffusion NMR
to measure blood glucose levels. Diffusion NMR separates mixture
components spectrally based on differing translational diffusion
coefficients of chemical species in solution. Therefore, example systems
and methods acquire NMR diffusion measurements of complex samples
including glucose and other chemicals found in the human body.

[0026] Example systems and methods may probe diffusion using pulsed field
gradient NMR. Pulsed field gradient NMR applies magnetic gradient pulses
to a sample located in a static magnetic field produced by the apparatus.
The magnetic field generated by the gradient pulse varies across the
sample. Therefore, molecules in one sample area are subjected to a
different magnetic field than molecules in a different sample area.
Therefore, the Larmor frequency of the molecules is different meaning
that the gradient pulse phase encodes spins according to molecular
position. After the gradient pulse, molecules may diffuse from one sample
location to another sample location. After a period of time, a dephasing
gradient is applied to reverse the phase change produced by the encoding
gradient. If an encoded molecule has moved from one location to another,
then it will not have its phase encoding reversed and will not be
decoded.

[0027] A nearly identical effect occurs when the field gradient or
inhomogeneity is constant or nearly constant in time. RF pulses are
applied and the decay rate of the signal represents both the intrinsic
relaxation of the molecule under investigation as well as additional
relaxation due to diffusion. Thus, either system configuration can result
in an accurate measurement of molecular motion or diffusion.

[0028] In one example, a sample is subjected to a radio frequency (RF)
pulse. The sample includes fluid in which glucose may be present. The RF
pulse turns the equilibrium magnetization M0 in the sample into the
transverse plane, which is perpendicular to the main static magnetic
field B0. The magnetization vector rotates around B0 at an angular
frequency ω=dφ/dt given by the Larmor equation:

ω=γB0

[0029] where γ is the gyromagnetic ratio (γ=2π×42.576
rad s-1 T-1 for a hydrogen proton).

[0030] After the initial excitation by the RF pulse, some additional
magnetic field is present. This could take the form of an inhomogeneous
main field or a gradient field G(x,y,z). For example, applying G(x)
changes B0 to a spatially variable field B (x,y,z)=B0+G(x,y,z) where
G(x,y,z) is substantially non-zero over some fraction of the sensitive
volume of the system. A similar formulation can be made in the case of an
inhomogeneous main field. Because the field is now spatially varying,
Larmor frequencies become different at different places in the sample.
Thus, after some period of time, some phase differences may have
accumulated between the spins at different positions.

[0031] After waiting for a diffusion time t=nΔt, an additional RF
pulse is applied that flips the spins in the transverse plane. This
causes the spins to start to rephase according to their spatial position
in the field inhomogeneity. For spins that did not change positions
during the diffusion time, the phase differences will be completely
reversed. For spins that did change position during the diffusion time,
they will not see exactly the same inhomogeneity, and thus, the spins
will not exactly reverse phase difference from the first period. This
incomplete reversal yields a phase dispersion in the measured sample.
Faster diffusion means that the spins have more opportunity to travel
farther and therefore experience larger magnetic field changes. Slower
diffusion means that spins have less opportunity to travel and therefore
experience smaller magnetic field changes. Diffusion speed in the
interstitial fluid is affect by the amount of glucose in the fluid.
Therefore, the described NMR methods can be used to measure blood glucose
levels.

[0032] FIG. 1 illustrates an embodiment of a NMR apparatus 100 for
determining the amount of a chemical species in a sample. The NMR
apparatus includes a first field generator 110 that is configured to
provide a first magnetic field 115 suitable for NMR. The first magnetic
field 115 may be a static inhomogeneous applied magnetic field configured
not to change in time. The first magnetic field 115 is sufficiently large
to encompass a sample 150 or a region of interest of the sample 150.

[0033] A pulse generator 120 provides a first RF pulse sequence. The pulse
generator 120 uses frequencies associated with NMR. The RF pulse sequence
may include a first RF pulse 123 to excite nuclei associated with a
chemical species 160 in the sample 150. The pulse sequence may also
include a second RF pulse 127 to cause the nuclei of the chemical species
160 to rephase according to their spatial position in the first magnetic
field 115. The frequency of the RF pulse sequence is chosen to produce an
NMR signal associated with a specific chemical species 160 (e.g.,
glucose) in the sample 150 (e.g., blood, tissue, organ). The amount of
the chemical species 160 in the sample 150 can be measured as a function
of the decay of the NMR signal. A phase logic 130 is configured to
measure the NMR signal decay.

[0034] The phase logic 130 measures NMR signal decay by measuring the
phase differences that have accumulated between the spins of the nuclei
of the chemical species 160 in the sample 150. The NMR signal may be used
to discern information about the chemical species 150 in the sample 160.
In one embodiment, the NMR signal decay represents, at least in part, the
intrinsic relaxation of the chemical species 160. In another embodiment,
the NMR signal decay may represent decay due to diffusion.

[0035] The sample 150 may be a interstitial fluid and the chemical species
160 may be glucose. Interstitial fluid is capable of diffusion in the
body. Therefore, the phase logic 130 may be configured to measure NMR
diffusion. In one embodiment, the pulse generator is configured to
initially excite the nuclei of the chemical species 160 with a first RF
pulse 123. The pulse generator is configured to apply a second RF pulse
127 to the sample 150. The second RF pulse 127 causes the spins of the
nuclei of the chemical species 160 in the sample 150 to rephase based on
their position in the first magnetic field 115.

[0036] A calculation logic 140 is configured to measure the amount of the
chemical species 160 (e.g., glucose) in the sample 150 (e.g.,
interstitial fluid) as a function of the NMR signal decay. If the nuclei
of the glucose were able to travel through interstitial fluid, the
glucose would experience larger magnetic field changes. Therefore, if the
glucose experiences larger magnetic field changes, the interstitial fluid
was able to diffuse more quickly indicating less glucose in the
interstitial fluid. Conversely, if the glucose experiences fewer magnetic
field changes, the glucose was not able to diffuse as quickly, indicating
more of the glucose in the interstitial fluid.

[0037] Recall that conventional NMR systems have issues associated with
size. The example apparatuses and methods do not require the use of
conventional NMR systems. Instead, NMR 100 apparatus may be a
miniaturized apparatus that produces very local conditions sufficient to
perform very local NMR. For example, the first field generator 110 may be
a small neodymium magnet used to generate a first magnetic field 115 that
will not change in time. The pulse generator 120 provides an RF pulse
sequence with an oscillation rate in a range of approximately 30 kHz to
300 GHz. A pulse generator 120 capable of this oscillation rate may be
very small and stamped on a small circuit board using surface mount
technology (SMT) or through hole technology (THT) mounts. In one
embodiment, the phase logic 130 and a calculation logic 140 are
implemented on a microprocessor. Accordingly, the NMR apparatus may be
sufficiently small to be mobile.

[0038] In one embodiment, NMR apparatus 100 is mobile to be more practical
for patients that may require constant measurements of a chemical species
160 in their bodies. For example, a diabetic patient may require
substantially constant monitoring of glucose levels in the blood. A
mobile NMR apparatus 100 may be wearable or implantable. Rather than
incessant finger pricks or invasive probing (e.g. catheter), a mobile NMR
device that could be worn (e.g. in manner of a watch, pendant) or
implanted allows a patient a greater degree of freedom and convenience.
Furthermore, a wearable or implantable NMR apparatus 100 does not
introduce the risk of infection of its transdermal counterparts (e.g.
finger prick, probe, catheter).

[0039] FIG. 2 illustrates an embodiment of NMR apparatus 100 that is
configured with a therapeutic logic 170. In this embodiment, the
therapeutic logic 170 is configured to determine an amount of insulin to
be administered to a patient as a function of the measure of the amount
of the chemical species 160 (e.g., glucose) in the sample 150 (e.g.,
interstitial fluid, blood).

[0040] In one embodiment, the calculation logic 140 may measure the amount
of chemical species 160 in the sample 150 based on a diffusion rate that
is determined to be low. If the measurement of the chemical species 160
in the sample 150 is outside of a predetermined range, the therapeutic
logic 170 may determine an amount of insulin to be administered to the
patient corresponding to the measured amount of chemical species 160 in
the sample 150.

[0041] Recall that there are several opportunities for error when a
patient attempts to determine the correct amount of insulin to give
self-administer. Therefore, the therapeutic logic 170 determining the
correct amount of insulin for the patient, rather than having a patient
calculate the amount of insulin, eliminates an opportunity for error. To
further reduce the opportunity for error, the NMR apparatus 100 may
include an insulin pump to administer the amount of insulin to the
patient.

[0042] FIG. 3 illustrates an embodiment of an NMR apparatus 100 that is
configured with an insulin pump 180 and a feedback logic 190. The insulin
pump 180 is configured to administer to the patient the amount of insulin
determined by the therapeutic logic 170. The feedback logic 190 is
configured to adjust the amount of insulin administered to the patient as
a function of a change in the measurement of the amount of the chemical
160 species in the sample 150.

[0043] In one embodiment, the calculation logic 140 determines an amount
of chemical species 160 (e.g., glucose) in a sample 150 (e.g.,
interstitial fluid, blood). A therapeutic logic 170 determines the amount
of insulin to be administered to the patient based, at least in part, on
the amount of chemical species 160 in the sample 150. In response to the
therapeutic logic 170 determining the amount of insulin to be
administered to the patient, the insulin pump 180 administers the amount
of insulin to the patient. The feedback logic 190 will adjust the amount
of insulin administered to the patient as the amount of chemical species
160 in the sample 150 changes.

[0044] Recall that the blood glucose levels of a diabetic patient vary
throughout the day as a function of many variables (e.g., types of food
consumed, when food is consumed, how much food is consumed, exercise
habits). Therefore, patients must consistently monitor their glucose
levels throughout the day and may need varying amounts of insulin based
on their insulin level at any given time. The feedback logic 190 allows
the insulin pump 180 to administer varying amounts of insulin as a
function of a change in the measured amount of glucose in a blood sample.

[0045] FIG. 4 illustrates an embodiment of an NMR apparatus 100 that is
configured with a second field generator 210. The second field generator
210 is configured to apply a second magnetic field 215. The second
magnetic field 215 may be spatially inhomogeneous, a pulsed field
gradient, or a constant field. The first magnetic field 115 and the
second magnetic field 215 are applied so that the first magnetic field
115 and the second magnetic field 215 can be applied to the sample 150.

[0046] In one embodiment, the second magnetic field 215 affects the pulse
sequence applied by the pulse generator 120. In one embodiment, the NMR
apparatus 100 may be used to measure the diffusion of the chemical
species 160 in a sample 150. Accordingly, the pulse generator 120 may
apply derivatives of the stimulated echo pulse sequence (PFG-STE). The
pulse generator 120 may apply pulses in pairs. Specifically, the pairs
may be bipolar pairs of gradient pulses to reduce artifacts in diffusion
spectra.

[0047] In one embodiment, the pulse generator 120 provides the RF sequence
a plurality of times. The NMR signal decay is measured by comparing a
plurality of NMR signals acquired after the pulse generator 120 has
provided the RF sequence a plurality of times.

[0048] FIG. 5 illustrates a method associated with of an NMR apparatus for
determining the amount of a chemical species in a sample. For example,
the method 500 may be employed to determine the amount of glucose in a
blood sample.

[0049] Method 500 includes, at 510, controlling an NMR apparatus to apply
a first magnetic field to a sample in a patient and to apply a RF pulse
sequence to produce an NMR signal in nuclei associated with a chemical
species in the sample.

[0050] Method 500 also includes, at 520, acquiring NMR signal decay data
associated with a decay of the NMR signal produced in response to
applying the first magnetic field and the RF signal.

[0051] Method 500 also includes, at 530, producing a characterization of a
chemical species in the sample as a function of the NMR signal decay
data. One of ordinary skill in the art will appreciate that the
characterization includes information about the chemical species in the
sample including, but not limited to, the amount of the chemical species
in the sample, and the diffusion rate of the chemical species in the
sample.

[0052] FIG. 6 illustrates a method 600 associated with of an NMR apparatus
for determining the amount of a chemical species in a sample. Method 600
includes, at 610, controlling a NMR apparatus to apply a first magnetic
field to a sample in a patient. The first magnetic field may be a static
inhomogeneous applied magnetic field configured not to change in time.

[0053] Method 600 also includes, at 620, controlling the NMR apparatus to
apply a second magnetic field to the sample. The second magnetic field
may be a pulsed field gradient or a constant field gradient. In one
embodiment, applying the first magnetic field at 610, and applying the
second magnetic field at 620, is done in a manner that produces a
spatially inhomogeneous field.

[0054] Method 600 also includes, at 630, applying an RF signal. The RF
signal may be configured as a pulse sequence including a first RF pulse
and a second RF pulse. The RF signal is configured to produce an NMR
signal in nuclei associated with a chemical species in the sample located
in the first magnetic field.

[0055] Method 600 also includes, at 640, acquiring NMR signal decay data
associated with a decay of the NMR signal produced in response to
applying the first magnetic field and the RF signal. The signal decay
data may be used to discern information about the chemical species in the
sample. For example, the NMR signal data may represent decay due to
diffusion.

[0056] Method 600 also includes, at 650, producing a characterization of a
chemical species in the sample as a function of the NMR signal decay
data. The characterization of a chemical species in the sample may be a
measurement at a specific point in time or continually track the chemical
species in the sample to measure changes in the chemical species in the
sample (e.g., amount of chemical species in the sample).

[0057] Method 600 includes, at 660, controlling an insulin providing
apparatus to provide a first dosage of insulin to the patient based, at
least in part, on the amount of the chemical species in the sample.

[0058] Method 600 includes, at 670, controlling an insulin providing
apparatus to provide a second different dosage of insulin to the patient,
based at least in part, on a change in the characterization of the
chemical species in the sample.

[0059] To the extent that the term "includes" or "including" is employed
in the detailed description or the claims, it is intended to be inclusive
in a manner similar to the term "comprising" as that term is interpreted
when employed as a transitional word in a claim.

[0060] While example systems, methods, and so on have been illustrated by
describing examples, and while the examples have been described in
considerable detail, it is not the intention of the applicants to
restrict or in any way limit the scope of the appended claims to such
detail. It is, of course, not possible to describe every conceivable
combination of components or methodologies for purposes of describing the
systems, methods, and so on described herein. Therefore, the invention is
not limited to the specific details, the representative apparatus, and
illustrative examples shown and described. Thus, this application is
intended to embrace alterations, modifications, and variations that fall
within the scope of the appended claims

Patent applications by Mark A. Griswold, Shaker Heights, OH US

Patent applications in class Including any system component contacting (internal or external) or conforming to body or body part

Patent applications in all subclasses Including any system component contacting (internal or external) or conforming to body or body part